Many animal species live in fluid fission-fusion societies, where the size and composition of conspecific groups change in space and time. To help investigate such phenomena, social network analysis (SNA) has emerged as a framework for assessing patterns of interconnectedness and quantifying group-level interactions. Social behavior in snakes is under-studied and, as a result, poorly known. Using social network analysis, Tetzlaff et al. (2023) examined social behavior in the Western Diamondback Rattlesnake, Crotalus atrox, from 2001 to 2015. They used behavioral observations via radiotelemetry and genotypic data from a long-term (>10 years) study of the Western Diamondback Rattlesnake. They used social networks to quantify the first robust demonstration of social network structures for any free-living snake species. Group-level interactions among adults in this population resulted in distinct clusters of interacting individuals for fidelity use of communal winter dens (denning network), mating behaviors (pairing network), and offspring production (parentage network). Although the structure of each network was similar, the size and composition of groups varied among them. Specifically, adults associated with moderately sized social groups at winter dens but often engaged in reproductive behaviors at and away from dens with different and fewer partners. Additionally, modules formed by individuals in the pairing network frequently differed from those in the parentage network, likely due to multiple mating, long-term sperm storage by females, and resultant multiple paternity. Further evidence for fission-fusion dynamics exhibited by this population interactions was rare when snakes dispersed to and traversed their spring-summer home ranges (to which individuals show high fidelity) despite ample opportunities to associate with numerous conspecifics with highly overlapping fields. The authors suggest that long-term datasets incorporating SNA with spatial and genetic information provide robust and unique insights into understanding the social structure of understudied cryptic taxa.

Citation
Tetzlaff SJ, Vizentin‐Bugoni J, Sperry JH, Davis MA, Clark RW, Repp RA, Schuett GW. 2023. Fission–fusion dynamics in the social networks of a North American pitviper. Ecology and Evolution 13(8):e10339.